Shioya N, Shimoaka T, Eda K, Hasegawa T
Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Phys Chem Chem Phys. 2015 May 28;17(20):13472-9. doi: 10.1039/c5cp01024a.
The molecular structure of poly(3-alkylthiophene-2,5-diyl) in an amorphous film reveals that the short axis of the thiophene ring is kept highly oriented parallel to the substrate, whereas the long axis along the polymer chain is largely disordered. This is unveiled by infrared p-polarized multiple-angle incidence resolution spectroscopy (pMAIRS), achieved by analyzing the orientation angles of three mutually orthogonal vibrational modes localized on the thiophene ring with the aid of a newly developed structural index. This new analytical technique is useful irrespective of the crystallinity of the thin film. As a result, the intrinsic chemical parameters controlling the molecular orientation are understood in a unified manner, and the reason that the hexyl group gives the best results for a photovoltaic cell is also revealed.
非晶薄膜中聚（3-烷基噻吩-2,5-二亚基）的分子结构表明，噻吩环的短轴保持高度平行于基底取向，而沿聚合物链的长轴则基本无序。这是通过红外p偏振多角度入射分辨光谱（pMAIRS）揭示的，借助新开发的结构指数分析噻吩环上三个相互正交振动模式的取向角得以实现。这种新的分析技术无论薄膜的结晶度如何都很有用。结果，以统一的方式理解了控制分子取向的内在化学参数，并且还揭示了己基在光伏电池中产生最佳效果的原因。
